Fast forward to today, Alegre is running one of the fastest-growing game discovery platforms and mobile ad networks in Silicon Valley — one that we’ve heard from three separate sources grossed about $50 million last year. (The company doesn’t comment on revenue figures). Her company Chartboost is quietly sucking in talent from an older generation of mobile ad networks and gaming studios like Google’s AdMob, DeNA’s Ngmoco and EA’s Popcap. They also picked up $19 million in funding led by storied VC firm Sequoia earlier this year.

“It’s kind of crazy. This all happened in four years,” she said. “Anyone can do it. People running these companies are not super humans. They are just people like you and me.”

While other competing startups with mobile advertising products were less focused, Chartboost wedged itself into the gaming world where it built an early platform for developers to trade advertising inventory. Because games are the biggest category for apps in terms of time spent on iOS and Android, it was the ideal place to build a focused business. Chartboost earns revenue through excess inventory, which can be sold in an exchange.

Chartboost now has 16,000 games in its network and 8 billion ad impressions per month and has grown 30 percent since January. Instead of the old banner ads, which had poor clickthrough rates, Chartboost instead focused on creating interstitials that looked and felt like they belonged in a game.

At first, it wasn’t easy, however. Alegre said that when she and her co-founder Sean Fannan were starting out, they did 30 phone pitches to potential investors in a week. In late 2011, they picked up a small round from TransLink Capital, SK Telecom Ventures and XG Ventures.

But after the business starting gaining momentum, it was very different with the second round. Jim Goetz, the Sequoia partner who led the firm’s investment in earlier mobile advertising network AdMob, got Chartboost’s model right away and invested quickly in the company.

“We were more picky with who to talk to,” she said. “The numbers don’t lie.”